在服务器插件可以使用之前，必须使用以下方法之一进行安装。在描述中，plugin_name 代表插件名称，例如 innodb、csv 或 validate_password。Before a server plugin can be used, it must be installed using one of the following methods. In the descriptions, plugin_name stands for a plugin name such as innodb, csv, or validate_password.

内置插件Built-in Plugins

服务器会自动识别内置插件。默认情况下，服务器在启动时启用该插件。某些内置插件允许使用 --plugin_name[=activation_state] 选项更改此设置。A built-in plugin is known by the server automatically. By default, the server enables the plugin at startup. Some built-in plugins permit this to be changed with the --plugin_name[=activation_state] option.

在 mysql.plugin 系统表中注册的插件Plugins Registered in the mysql.plugin System Table

mysql.plugin 系统表用作插件的注册表（内置插件除外，内置插件无需注册）。在正常启动序列中，服务器会加载在表中注册的插件。默认情况下，对于从 mysql.plugin 表加载的插件，服务器也会启用该插件。可以通过 --plugin_name[=activation_state] 选项进行更改。The mysql.plugin system table serves as a registry of plugins (other than built-in plugins, which need not be registered). During the normal startup sequence, the server loads plugins registered in the table. By default, for a plugin loaded from the mysql.plugin table, the server also enables the plugin. This can be changed with the --plugin_name[=activation_state] option.

如果服务器使用 --skip-grant-tables 选项启动，则 mysql.plugin 表中注册的插件不会被加载，也不可用。If the server is started with the --skip-grant-tables option, plugins registered in the mysql.plugin table are not loaded and are unavailable.

通过命令行选项指定的插件Plugins Named with Command-Line Options

位于插件库文件中的插件可以在服务器启动时通过 --plugin-load、--plugin-load-add 或 --early-plugin-load 选项加载。通常，对于在启动时加载的插件，服务器也会启用该插件。可以通过 --plugin_name[=activation_state] 选项更改此设置。A plugin located in a plugin library file can be loaded at server startup with the --plugin-load, --plugin-load-add, or --early-plugin-load option. Normally, for a plugin loaded at startup, the server also enables the plugin. This can be changed with the --plugin_name[=activation_state] option.

--plugin-load 和 --plugin-load-add 选项在服务器启动序列中内置插件和存储引擎初始化之后加载插件。--early-plugin-load 选项用于加载必须在内置插件和存储引擎初始化之前可用的插件。The --plugin-load and --plugin-load-add options load plugins after built-in plugins and storage engines have initialized during the server startup sequence. The --early-plugin-load option is used to load plugins that must be available prior to initialization of built-in plugins and storage engines.

每个插件加载选项的值是由plugin_library和name=plugin_library值组成的分号分隔列表。每个plugin_library是包含插件代码的库文件的名称，每个name是要加载的插件名称。如果插件库仅以库名命名而没有前置插件名称，服务器将加载库中的所有插件。如果有前置插件名称，服务器将仅从库中加载指定的插件。服务器会在由plugin_dir系统变量指定的目录中查找插件库文件。The value of each plugin-loading option is a semicolon-separated list of plugin_library and name=plugin_library values. Each plugin_library is the name of a library file that contains plugin code, and each name is the name of a plugin to load. If a plugin library is named without any preceding plugin name, the server loads all plugins in the library. With a preceding plugin name, the server loads only the named plugin from the library. The server looks for plugin library files in the directory named by the plugin_dir system variable.

插件加载选项不会在 mysql.plugin 表中注册任何插件。对于随后的重启，服务器仅在再次给出 --plugin-load、--plugin-load-add 或 --early-plugin-load 时才会再次加载插件。也就是说，该选项执行一次性插件安装操作，仅在单次服务器调用中有效。Plugin-loading options do not register any plugin in the mysql.plugin table. For subsequent restarts, the server loads the plugin again only if --plugin-load, --plugin-load-add, or --early-plugin-load is given again. That is, the option produces a one-time plugin-installation operation that persists for a single server invocation.

--plugin-load、--plugin-load-add 和 --early-plugin-load 允许即使在指定 --skip-grant-tables 时也能加载插件（这会导致服务器忽略 mysql.plugin 表）。--plugin-load、--plugin-load-add 和 --early-plugin-load 也允许在启动时加载那些运行时无法加载的插件。--plugin-load, --plugin-load-add, and --early-plugin-load enable plugins to be loaded even when --skip-grant-tables is given (which causes the server to ignore the mysql.plugin table). --plugin-load, --plugin-load-add, and --early-plugin-load also enable plugins to be loaded at startup that cannot be loaded at runtime.

--plugin-load-add 选项补充了 --plugin-load 选项：The --plugin-load-add option complements the --plugin-load option:

例如，这些选项：For example, these options:

--plugin-load=x --plugin-load-add=y

等同于这些选项：are equivalent to these options:

--plugin-load-add=x --plugin-load-add=y

也等同于这个选项：and are also equivalent to this option:

--plugin-load="x;y"

但这些选项：But these options:

--plugin-load-add=y --plugin-load=x

相当于此选项：are equivalent to this option:

--plugin-load=x

使用 INSTALL PLUGIN 语句安装的插件Plugins Installed with the INSTALL PLUGIN Statement

位于插件库文件中的插件可以在运行时通过 INSTALL PLUGIN 语句加载。该语句还会在 mysql.plugin 表中注册该插件，以便服务器在后续重启时加载它。因此，INSTALL PLUGIN 需要对 mysql.plugin 表具有 INSERT 权限。A plugin located in a plugin library file can be loaded at runtime with the INSTALL PLUGIN statement. The statement also registers the plugin in the mysql.plugin table to cause the server to load it on subsequent restarts. For this reason, INSTALL PLUGIN requires the INSERT privilege for the mysql.plugin table.

插件库文件的基本名称取决于您的平台。常见的后缀是 .so 用于 Unix 和类 Unix 系统，.dll 用于 Windows。The plugin library file base name depends on your platform. Common suffixes are .so for Unix and Unix-like systems, .dll for Windows.

示例：--plugin-load-add 选项在服务器启动时安装插件。要从名为 somepluglib.so 的插件库文件安装名为 myplugin 的插件，可在 my.cnf 文件中使用以下内容：Example: The --plugin-load-add option installs a plugin at server startup. To install a plugin named myplugin from a plugin library file named somepluglib.so, use these lines in a my.cnf file:

[mysqld]
plugin-load-add=myplugin=somepluglib.so

在这种情况下，插件不会在 mysql.plugin 中注册。如果在没有 --plugin-load-add 选项的情况下重启服务器，则插件不会在启动时加载。In this case, the plugin is not registered in mysql.plugin. Restarting the server without the --plugin-load-add option causes the plugin not to be loaded at startup.

或者，INSTALL PLUGIN 语句会导致服务器在运行时从库文件加载插件代码：Alternatively, the INSTALL PLUGIN statement causes the server to load the plugin code from the library file at runtime:

INSTALL PLUGIN myplugin SONAME 'somepluglib.so';

INSTALL PLUGIN 还会导致“永久” 插件注册：该插件会被列在 mysql.plugin 表中，以确保服务器在后续重启时加载它。INSTALL PLUGIN also causes “permanent” plugin registration: The plugin is listed in the mysql.plugin table to ensure that the server loads it on subsequent restarts.

许多插件可以在服务器启动时或运行时加载。然而，如果一个插件的设计要求它必须在服务器启动时加载和初始化，则在运行时尝试使用 INSTALL PLUGIN 加载它会产生错误：Many plugins can be loaded either at server startup or at runtime. However, if a plugin is designed such that it must be loaded and initialized during server startup, attempts to load it at runtime using INSTALL PLUGIN produce an error:

mysql> INSTALL PLUGIN myplugin SONAME 'somepluglib.so';
ERROR 1721 (HY000): Plugin 'myplugin' is marked as not dynamically
installable. You have to stop the server to install it.

在这种情况下，您必须使用 --plugin-load、--plugin-load-add 或 --early-plugin-load。In this case, you must use --plugin-load, --plugin-load-add, or --early-plugin-load.

如果一个插件既通过 --plugin-load、--plugin-load-add 或 --early-plugin-load 选项命名，又由于之前的 INSTALL PLUGIN 语句已存在于 mysql.plugin 表中，服务器启动时会写入这些消息到错误日志：If a plugin is named both using a --plugin-load, --plugin-load-add, or --early-plugin-load option and (as a result of an earlier INSTALL PLUGIN statement) in the mysql.plugin table, the server starts but writes these messages to the error log:

[ERROR] Function 'plugin_name' already exists
[Warning] Couldn't load plugin named 'plugin_name'
with soname 'plugin_object_file'.

如果服务器在启动时知道某个插件（例如，因为插件使用 --plugin-load-add 选项命名，或者在 mysql.plugin 表中注册），服务器默认会加载并启用该插件。可以使用 --plugin_name[=activation_state] 启动选项来控制此类插件的激活状态，其中 plugin_name 是要影响的插件名称，例如 innodb、csv 或 validate_password。与其他选项一样，选项名称中的连字符和下划线可以互换。此外，激活状态值不区分大小写。例如，--my_plugin=ON 和 --my-plugin=on 是等价的。If the server knows about a plugin when it starts (for example, because the plugin is named using a --plugin-load-add option or is registered in the mysql.plugin table), the server loads and enables the plugin by default. It is possible to control activation state for such a plugin using a --plugin_name[=activation_state] startup option, where plugin_name is the name of the plugin to affect, such as innodb, csv, or validate_password. As with other options, dashes and underscores are interchangeable in option names. Also, activation state values are not case-sensitive. For example, --my_plugin=ON and --my-plugin=on are equivalent.

插件激活状态可以在信息模式中的LOAD_OPTION列看到，参见PLUGINS表。Plugin activation states are visible in the LOAD_OPTION column of the Information Schema PLUGINS table.

假设 CSV、BLACKHOLE 和 ARCHIVE 是内置的可插拔存储引擎，并且你希望服务器在启动时加载它们，但需满足以下条件：如果 CSV 初始化失败，服务器仍允许运行；必须确保 BLACKHOLE 初始化成功；并且应该禁用 ARCHIVE。为实现这一点，在选项文件中使用以下几行：Suppose that CSV, BLACKHOLE, and ARCHIVE are built-in pluggable storage engines and that you want the server to load them at startup, subject to these conditions: The server is permitted to run if CSV initialization fails, must require that BLACKHOLE initialization succeeds, and should disable ARCHIVE. To accomplish that, use these lines in an option file:

[mysqld]
csv=ON
blackhole=FORCE
archive=OFF

--enable-plugin_name 选项格式是 --plugin_name=ON 的同义词。--disable-plugin_name 和 --skip-plugin_name 选项格式是 --plugin_name=OFF 的同义词。The --enable-plugin_name option format is a synonym for --plugin_name=ON. The --disable-plugin_name and --skip-plugin_name option formats are synonyms for --plugin_name=OFF.

如果插件被禁用，无论是通过 OFF 明确禁用，还是因为以 ON 启用但初始化失败而隐式禁用，服务器操作中依赖该插件的部分就会发生变化。例如，如果该插件实现了一个存储引擎，那么现有的该存储引擎的表将无法访问，并且尝试为该存储引擎创建新表将会生成使用默认存储引擎的表，除非启用了 NO_ENGINE_SUBSTITUTION SQL 模式，使其改为报错。If a plugin is disabled, either explicitly with OFF or implicitly because it was enabled with ON but fails to initialize, aspects of server operation requiring the plugin change. For example, if the plugin implements a storage engine, existing tables for the storage engine become inaccessible, and attempts to create new tables for the storage engine result in tables that use the default storage engine unless the NO_ENGINE_SUBSTITUTION SQL mode is enabled to cause an error to occur instead.

禁用插件可能需要调整其他选项。Disabling a plugin may require adjustment to other options.

在运行时，UNINSTALL PLUGIN 语句会禁用并卸载服务器已知的插件。该语句会卸载插件并将其从 mysql.plugin 系统表中移除（如果插件已在该表中注册）。因此，UNINSTALL PLUGIN 语句需要对 mysql.plugin 表具有 DELETE 权限。在插件不再在表中注册后，服务器在随后的重启中不会加载该插件。At runtime, the UNINSTALL PLUGIN statement disables and uninstalls a plugin known to the server. The statement unloads the plugin and removes it from the mysql.plugin system table, if it is registered there. For this reason, UNINSTALL PLUGIN statement requires the DELETE privilege for the mysql.plugin table. With the plugin no longer registered in the table, the server does not load the plugin during subsequent restarts.

UNINSTALL PLUGIN 可以卸载插件，无论它是在运行时通过 INSTALL PLUGIN 加载的，还是在启动时通过插件加载选项加载的，但需满足以下条件：UNINSTALL PLUGIN can unload a plugin regardless of whether it was loaded at runtime with INSTALL PLUGIN or at startup with a plugin-loading option, subject to these conditions:

要卸载当前使用插件加载选项在服务器启动时加载的插件，请使用此步骤。To uninstall a plugin that currently is loaded at server startup with a plugin-loading option, use this procedure.

当插件安装时，它也可能会自动安装相关的可加载功能。如果是这样，当插件被卸载时，也会自动卸载这些功能。A plugin when installed may also automatically install related loadable functions. If so, the plugin when uninstalled also automatically uninstalls those functions.